1. Field of the Invention
The present invention relates to an electrostatic accelerator incorporating an accelerating column, a high voltage terminal at one end of said accelerating column and electric charge transport means.
2. Discussion of the Background
Such electrostatic accelerators of the Van de Graaf type are already known and have been used for accelerating ions in various nuclear physics research projects. Electrostatic accelerators also have other applications, particularly in the field of free electron lasers.
Electrostatic accelerators have numerous advantages in the latter field. They supply pulses, whose durations are very long compared with those of the pulses supplied by pulse-type or high frequency accelerators. The spectral width of the line emitted by a free electron laser associated with an electrostatic accelerator is very small. The quality of the electron beam accelerated by an electrostatic accelerator is excellent and well adapted to the requirements of free electron lasers. Such an accelerator makes it possible to recover with high efficiency the energy of the electron beam, following the passage of said beam through the cavity of said free electron laser associated with said accelerator. Due to the possibility of recovering the energy of the electron beam, the overall efficiency of the free electron laser is very high.
However, a Van de Graaf-type electrostatic accelerator still suffers from a disadvantage. The electric charge transport means incorporated in such an accelerator are in the form of a belt or some other mechanical transport device, such as e.g. a Pelletron or Laddertron. Therefore, in such an accelerator, the value of the charging current (current corresponding to said electric charges) is low.